Details
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Type:
Sub-task
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Status: Resolved
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Priority:
Minor
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Resolution: Fixed
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Affects Version/s: QuorumJournalManager (HDFS-3077)
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Fix Version/s: QuorumJournalManager (HDFS-3077)
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Component/s: None
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Labels:None
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Target Version/s:
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Hadoop Flags:Reviewed
Description
In order for QJM to work with HA, the standby needs to be able to read from a JournalNode even when no active has written to it. In the current code, it reads the StorageInfo only when newEpoch() is called. But, that's only called when a writer becomes active. This causes the SBN to fail at startup since the JN thinks its storage info is uninitialized.
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One tiny nit, you might want to put a space after ":" here:
System.err.println("storage string:" + storageString);
Otherwise the patch looks good to me. +1.
Committed to branch, with nit addressed in the commit. Thanks for reviewing.
Attached patch changes the StorageInfo to happen right when the journal is first accessed.
If the journal is unformatted, then it waits until a writer becomes active to format it (since that writer is the one who provides the NamespaceInfo with which to format).
The patch includes an update to the unit test to verify the improved behavior. A future functional test case which involves HA namenodes also depends on this, but this patch just has the targeted test.